The present disclosure is directed to electrochemical machining (ECM) and, more particularly, to an ECM system for use with additively manufactured components and methods of operation thereof.
Additive manufacturing is a technology that enables the “3D-printing” of components of various materials including metals and plastics. In additive manufacturing, a part is built in a layer-by-layer manner by leveling metal powder and selectively fusing the powder using a high-power laser. After each layer, more powder is added and the laser forms the next layer, simultaneously fusing it to the prior layers to fabricate a complete component buried in a powder bed. When removed from the powder bed, the component typically has a rough surface finish that must be improved via post-build processes such as grit blasting, grinding, sanding, or polishing to meet industry standards. These processes are known to improve surface finish for external easy-to-reach surfaces of the component, but are generally insufficient for internal passages that may be present. The surface finish of internal passages must be improved to mitigate component failures due to conditions such as low-cycle fatigue, high-cycle fatigue, and coking.
ECM is a method for improving surface finish. Due to the high metal removal rates of ECM, sufficient smoothing of surface finishes may be achieved without thermal or mechanical stresses being transferred to the component. In the ECM process, a cathode, or tool, is advanced toward an anode, or workpiece, typically the component. As an electrical potential difference is established between the between cathode and the anode, material from the anode is dissolved and electrolytic fluid carries away the dissolved metal compounds formed in the process. ECM can be applied to the internal surfaces of an additively manufactured component. However, the complex geometry of certain components prevents the cathode from gaining access to the internal surfaces to enable them to be machined. For example, internal passages may be larger than access ports that lead to the passages, thus requiring complex movement of the cathode. Additionally, the passages may twist and turn through a complex path, requiring a flexible cathode. Furthermore, the cathode must be electrically isolated from the component to prevent a short circuit and thus ensure successful surface finish enhancement of the internal passages using the ECM process.